The present invention relates to an imaging device having a dual lens optical system.
Recently, digital cameras have gradually become smaller and thinner. To this end, many cameras are adopting a refraction optical system. Also, many digital cameras are adopting a zoom optical system to improve convenience. However, as digital cameras become smaller and thinner, the inner space of the digital camera decreases so that there is a limit in adjusting the focal length using the zoom optical system. Accordingly, there is a limit in increasing the optical zoom ratio. A digital zoom is employed to compensate for the limit using software. However, since digital zoom uses a part of an image for magnification, image quality is deteriorates. Thus, the optical zoom ratio can be increased by simultaneously adopting the zoom optical system having a focal length in a standard range and a single focus optical system having a shorter focal length.
There are two conventional methods to adopt both of the different optical systems. The first method is to include a single image sensor and a plurality of optical systems and selectively use the appropriate optical system. The second method is to include a plurality of image sensors and a plurality of optical systems.
Japanese Patent Publication No. 10-254055 discloses an optical system using the first method. Referring to FIG. 1A, light passing through a first optical system 1 is reflected by a first reflection mirror 4 and incident on an image sensor 7. Referring to FIG. 1B, as the first reflection mirror 4 is moved to a vertical orientation, light passing through a second optical system 2 is reflected by a second reflection mirror 5 and incident on the image sensor 7. Referring to FIG. 1C, as the first and second reflection mirrors 4 and 5 are moved to the vertical orientation, light passing through a third optical system 3 is reflected by a third reflection mirror 6 and incident on the image sensor 7. Since all the optical systems 1, 2, and 3 to be adopted need to be included inside a compact camera, it is difficult to reduce the number of parts and make the camera compact.
Likewise, in an optical system using the second method, since the number of parts is further increased compared to the first method, it is difficult to reduce the costs for materials and make a camera compact.